console.log(
    `this,js开始运行`
)
var obj = {
    birth:1999,
    getAge:function(){
        var b = this.birth;
        var fn = () => new Date().getFullYear() - b;
        return fn()
    }
}
console.log(obj.getAge())
return
var x = 11;
var obj = {
    x:22,
    say:()=>{
        console.log(this.x);//11
    }
}
obj.say()
return
var name = 222
var a = {
    name: 111,
    say: function(){
        console.log(this.name)  
    }
}

var fun = a.say
fun() // undefined
a.say() // 111

var b = {
    name:333,
    say:function(fun){
        fun()
    }
}
b.say(a.say) //undefined
b.say = a.say 
b.say() ///333